A Superfuel? A hard look at Thorium myths

I like thorium as a fuel source a lot, and am optimistic about its future; but I think that articles like this are important. Its crucial to be scientific and objective when investigating the merits of different energy systems.

The authors are neither scientific nor objective. There are good reasons why none of the ~100 000 weapons built and deployed in nuclear arsenals was ever U233 based, which cannot be wished away by "it is theoretically possible".

The authors do not understand differences between thermal and fast spectrum, how these differences reflect on fissile needs, and how fuel reprocessing actually works - this is a chemical process and there are always losses. If you need 100x more fissile in a fast reactor to get the same amount of fission power, even 1% of TRU losses to the waste stream will kill your breeding and waste profile. What is more, we do not have working pyroprocessing at all, as of now, despite wild claims of IFR hypers.

Claiming that given 100% perfect reprocessing, the fast reactors can be as good as thorium MSR, is hyping vaporware and misunderstanding the reasons why ThMSR is actually attractive.

Fact: U233, bred from Thorium-232 is weaponizable. Because it wasn't done in bulk doesn't mean it couldn't be done in the future. This is what the public wants to know about. Therefore T-MSRs should have proliferation safeguards in place, just like regular reactors. Getting weapons from any civilian reactor is unlikely but technically possible. That's the key.

And regarding my supposed spectral ignorances, "thermal spectrum MSRs require <2 kg of fissile material per MWe to reach criticality compared with 3 to 5 kg/MWe for LWRs and over 25 kg/MWe for fast-spectrum reactors" [1], so it's more like a factor of 12.5 to achieve criticality. But where the fast spectrum shines is in its breeding ratio, which can approach 1.3 compared with 1.06 for the thermal MSR thanks to the astounding number of neutrons released per absorption (eta) in the fast spectrum. So even though there are up to 10% losses in proposed LMFBR reprocessing plants, they can keep up with MSRs, no problem. MSR processes will have losses too, of course.

Update: Actually, a more typical fissile/MWe number for SFRs is below 10. Looks like the first reference is mistaken. Here are a bunch of designs that use 3000kg of TRU to produce 400 MWe, so that's 7.7 kg/MWe, and this is in line with my design experience. ANL-AFCI-177

Theoretically almost anything is possible, in particular for experienced weaponeers. You are hiding the practical fact that fast spectrum reactors are actually very good at producing WG-Pu239, while U233 is impractical. The key is what is actually realistically feasible, has a high likelihood of success, and can use proven textbook / openly available technologies and designs. That is U235 or Pu239 routes. Experience shows that again and again. Theoretically it is possible to get weapons from seawater uranium and methane-derived graphite. Perhaps next "mythbusting" from whatisnucler - oceans breed warheads!

Regarding fissile inventory - there are "less then" and "greater then" signs, indicating limits. Breeding gain is not very useful, since it is not normalized per fissile needed, but per fissions occurred, and hard spectrum requires much more fissile to be loaded into the core for the same amount of fissions to occur. Therefore breeding gain in fast spectrum can quickly transform to breeding loss by small leaks of TRUs to the waste stream. 10% of TRU losses in proposed LMFBR means waste stream worse than LWR, and no breeding possible. Again, this is not 10% lost of what you bred, but 10% of all TRU, and if you want to close fuel cycle in U/Pu LMFBR, the fissile basically equals the TRU. Even 1% loss would kill your breeder.

Actually useful metrics is doubling time, which is about 20 years for LFMBR with ideal reprocessing, and about the same for a realistic MSBR. Theoretically can be less than 3 years for theoretical ThMSR with ideal reprocessing! I presume that is not the key.

In a two-fluid MSR you never get the fuel out, so you do not lose it to waste. Also since you never get the fuel out, there is much less worry about proliferation.

Also see my update above. 7.7 kg fissile/MWe is reasonable for SFRs, according to Argonne National Lab.

Doubling time is indeed a key metric and some two-fluid MSRs are hard to beat there. On the other hand, there is a pretty big safety concern with those because when the fertile fluid loop develops a leak it can insert a lot of negative reactivity. I haven't seen detailed transient calculations but it's worth checking out.

Right. Nothing is proliferation proof. Seawater is not proliferation proof.

I am not arguing there should be no safeguards. I am arguing a) that by the nature of it, Th-MSR is significantly less of a proliferation risk than alternatives - LWRs with their need for enrichment or fast reactors which need high fissile load and readily produce high grade Pu; b) that making a theoretical argument "in principle somebody may be able to use this for a bomb" a silly and counterproductive exercise.

I agree. But that's not how people who are not really interested react to technical issues, on face value. We could say they are better than the alternatives, but once U233 is brought up it can have it's issues.

Plus I don't think the global enrichment industry will just accept their industry going out of business. In the future there will be opportunities for both MSRs and LWRs (even HWRs), but the argument needs to shift from x reactor is better than y reactor to x and y reactors a better than a,b,c fossil fuel generators.

I dont think #2 is a myth. Yes, you need fissile material to start LFTR, but thats NOT the same as needing enrichment. We already have enough fissile materials to start many LFTRs, and once you have them running you can breed additional material with them. So LFTR economy wont need enrichment at all. Not initially (we already have enough material for the start), and not afterwards (once you have LFTRs running you can breed with them).

EDIT: also, a lot of these myths are more like "mostly true, but not exclusive to thorium". Which is correct, I always try to stress that many of LFTR advantages are present in other 4th generation designs, too.

The author isn't trying to change your mind about Thorium, just to bring the hype back to reality.

I'm not a nuclear engineer or nuclear physicist, but I have a deep interest in nuclear power and other industrial processes in general, so I've been keeping abreast of concepts in nuclear technology for about 15 years. While I didn't know anything about Thorium or the MSR before Kirk Sorensen's efforts brought it to my attention, I pretty quickly saw through the hype (usually not spread by Kirk himself, but by others) in much the same way this article attempts to do.

Fair point. But is there some other long-lived FP that is important from the U-233 yield in its place? I'd like to see a long term waste heat and toxicity study comparing Th-based MSRs, U-based MSR, and FRs with full recycle. Has anyone seen such a study? If not, I guess I can perform one and publish it if it's missing. I have the technology.

I've seen some pretty crappy thorium debunks, but this one was actually pretty good. Fast reactors do have a lot of the same advantages.

I do have a minor quibble on point #2. It's true that thorium reactors and fast reactors both breed their own fuel once you've gotten them started. However, fast reactors take five to ten times as much enriched fuel to get them started.

Consequently, we could convert civilization to run on thorium much more quickly than we could convert to fast reactors. The fast reactors would be limited by startup fuel, and each would take 7 to 8 years to breed enough fuel to replicate itself. If we want to build a lot of them fast we'd have to build more conventional plants too, and/or do a lot of enrichment. With liquid thorium reactors the startup fuel isn't likely to constrain us.

Author of OP's article here. Excellent point! I have added this point to the myths page:

It should be noted, however, that the key advantage of Th fuel is that it allows thermal breeding. This means that you can start up a Th-based breeder with substantially less fissile material than you need to start an equivalent-powered fast breeder reactor. Once started, the fast breeder will make far more fissile material (because they make have a better breeding neutron economy), but the amount of fissile in fast spectrum reactors is always more than in thermal reactors.

About the fan out, fuel cycle dynamics is very complicated and depends on how fast you want to fan out. If you need 100 reactors right now, then thermal is the way to go, but if you are doing a slower exponential fan-out, fast breeders might be better because they can make far more excess fissile. So that second point you make is more debatable than the first.

Sorenson used to have a page on his site with a scenario for a twenty-year conversion of the entire U.S. energy supply, but it relied on fast-spectrum molten salt reactors, which are probably a good bit further off. I haven't seen numbers on just what we could accomplish with existing materials.

The entire website feels heavily spun. Every upside is marred by a caveat, detailing specific problems at great length. Every downside is left stark, with no information on whether a given concern may be diminutive. It's informative, but certainly not fair.

I think he makes a good point here, and doesn't deserve to have his objectivity questioned for it. Breeding ratio for a thermal liquid thorium reactor is about 1.07, pretty close to unity given that you probably won't hit the ideal. Breeding ratio for a liquid-metal fast breeder is 1.4 in theory, with 1.2 actually achieved. source

It would be interesting to compare what could be achieved in various time frames with either design, given the materials we have to start with, and to figure out what the optimum strategy would be if we had both.

So I've been getting some decent aggressive mail from users about this article discussing some of the statements around Thorium.

If there is content in the article that is incorrect, please sate why and provide some source for the author /u/whatisnuclear. He's here to discuss and from what I've seen there is a lot of good discussion going on about the misconceptions and some that are being fleshed out.

If I offended anyone I apologise and didn't intend to do so. I found content that was interesting and would stoke some robust discussion on Thorium as a fuel in Molten Salt Reactors.

What I didn't expect is the aggressive threat laden private messages from Thorium advocates.

So I could react a couple of ways:

Be petty take the abuse personally and vow to screw Thorium over at every opportunity

Work to resolve the misconceptions that are discussed frequently with regards to all Nuclear

For #2, you don't need enrichment if you start the reactor on transuranium elements from used nuclear fuel. Fast breeders typically use HEU for driver fuel (EBR-1 and EBR-2), or close to the limits of LEU (19.75% enriched), since the cross-sections in the fast spectrum are tiny. This is a world of difference compared to the possibility of running on small amounts of fissile from wherever as in a thermal spectrum thorium MSR.

For #3, the same as the #1 above. Making bombs from U233 is much more difficult than from U235 or Pu239, which is why no U233 bombs are among the tens of thousands of world's nuclear weapons.

For #4, what the article does not say is that we already mine all the thorium we will ever need, as it occurs in most rare earth element (REE) deposits, it is just discarded with tails (or stockpiled, as China does now). In this sense the "economically recoverable reserve" amount does not matter, we already mine more than enough.

For #5, the authors have no clue about reprocessing and fast spectrum reactors. Fast spectrum needs about 50-100x more fissile for the same power, as the cross-sections are that much smaller. If you reprocess, you lose some of the transuranics to the waste stream. The technology suggested for fast reactor fuel cycles (pyroprocessing, specifically electrochemical refining) has currently TRU losses into waste in 2-10% range (depending on whom you believe), which makes it WORSE than LWR once-through cycle, and in addition negates any breeding gains. Even worse than that, there are still unresolved issues such as cadmium migration into the electrorefiner, which makes it unusable as of now. Talk about hype!

The major reason for using thorium MSR is that a) it is a thermal system with much lower fissile loads so you reprocess tiny amounts in comparison so your TRU wastes are proportionally tiny, b) the fuel cycle chemistry is straight forward and simple in comparison with IFR-like pyro.

U233 is too much trouble. There was a time during the Manhattan project, few months in late 1944, after the issue with spontaneous fission of Pu240 was realized, when people seriously considered U233 as an alternative. Only to find that U233 is even worse that the original problem they tried to solve.

Interesting note here is that this Pu to U233 converter concept was the original idea which then led to LWRs.

I've replied to most of these through discussions with my good friend /u/jamesnow since this was posted and he wants me to put them here, which I think is a great idea.

For myth number 1, we originally claimed that MSRs weren't developed because they couldn't make bombs. This was technically incorrect if you look back to the 40s, as you can see from Kirk's thesis. Back then, MSRs weren't capable of going critical on natural uranium, much less making bombs. I've changed the myth to say that MSRs weren't canceled in the '60s because of their (nonexistent) inability to make bombs. Regarding this updated myth, I've said:

In summary, I said that, while MSRs were certainly not developed in the '40s due to the fact that they couldn't even start up without enrichment, much less make bombs, the cancellation of their development in the 60s did not happen because of their inability to make bombs. My point is that in a post-enrichment world, MSRs can indeed make bombs so canceling them because they can't doesn't even make sense. They lost funding because the government at the time favored development of an alternative concept (the LMFBR). The LMFBR was NOT favored because it could make more bombs (bombs were made in production reactors), but rather because of nuanced political reasons discussed at length by Alvin Weinberg in his stellar autobiography, The First Nuclear Era. The MSR development was not canceled because it couldn't make bombs in the 60s. Fact.

For #2, you don't need enrichment if you start the reactor on transuranium elements from used nuclear fuel. Fast breeders typically use HEU for driver fuel (EBR-1 and EBR-2), or close to the limits of LEU (19.75% enriched), since the cross-sections in the fast spectrum are tiny. This is a world of difference compared to the possibility of running on small amounts of fissile from wherever as in a thermal spectrum thorium MSR.

We've been noticing some sources say things like Th reactors don't need any enrichment at all. The clarification made by us in Myth 2 is that these reactors would indeed need some form of enriched fissile material to turn on. Furthermore, any breeder reactor can become fissile self-sufficient. Yes, FBRs require about 3x more fissile per GWt to start up, but once they are operating, their breeding ratios are phenomenal thanks to their very hard spectrum (and the fact that value of eta becomes very high in the hard spectrum) so they can make up for it, no problem. So the initial fissile needed to start up isn't a huge deal compared to a fissile self-sufficient fleet. Maybe these points could be made slightly less abrasive. I will think about it to get you guys onboard.

For #3, the same as the #1 above. Making bombs from U233 is much more difficult than from U235 or Pu239, which is why no U233 bombs are among the tens of thousands of world's nuclear weapons.

I've discussed this endlessly. People were saying that Th reactors CANNOT be used to make a bomb. This is false; they sure can make bombs! And it's not all that impossible or difficult really, as I've discussed and referenced at length. The claim that the only reason U235/Pu239 bombs are so plentiful is that they are easier to make is perfectly analogous to the (equally false) statement that LWRs are infinitely more plentiful than MSRs because LWRs were so much easier to make. Count it. ;)

For #5, the authors have no clue about reprocessing and fast spectrum reactors. Fast spectrum needs about 50-100x more fissile for the same power, as the cross-sections are that much smaller. If you reprocess, you lose some of the transuranics to the waste stream. The technology suggested for fast reactor fuel cycles (pyroprocessing, specifically electrochemical refining) has currently TRU losses into waste in 2-10% range (depending on whom you believe), which makes it WORSE than LWR once-through cycle, and in addition negates any breeding gains. Even worse than that, there are still unresolved issues such as cadmium migration into the electrorefiner, which makes it unusable as of now. Talk about hype!

Aww, that hurts my feelings :( but it doesn't change the fact that the correct number is less than ten. Closed cycles are not worse than LWRs. There is certainly work to be done in FBR reprocessing technology, but we have far far far far far less experience with MSR-type reprocessing. What are the losses in MSR closed-cycle processing? So it's really hard to make comparisons between the two. In fact, there is some technology overlap between FBR and MSR reprocessing so it'd be cool if we could fund research that helps both out, because both do need some work, both technically and to bring costs down.

U233 is a great weapons material. The fact that there weren't the resourced during WWII to develop three different types of weapon doesn't mean it wouldn't be possible today. I can't see why anybody would use U233 for weapons, but they could. The thorium itself does not confer any particular proliferation resistance - this is a function of the reactor technology. Kirk Sorensen plays down the proliferation issues because his preferred reactor contains highly enriched uranium. In general, this would make licensing of a civilian power plant extremely challenging, U232 or not.

"U-233 has been shown to be highly satisfactory as a weapons material; however, it has substantial technical advantage over plutonium only in certain environments, and the probability of such environments being encountered is quite low. LRL is quick to point out that conditions are subject to change and reappraisal, but as of today, they have no plans for developing weapons systems using U-233.

The statement was made that if today's weapons were based upon U-233, LRL would have no interest in switching to plutonium."

Yes pure U233 is great. The problem is that you cannot produce it in any realistic power reactor. The pure U233 was produced at the edges of production reactors where there is low and purely thermal flux, which means it takes forever to get any useful quantity. In another words, anybody able to make U233 weapon would already have capabilities to make several advanced bombs, and any playing with U233 is musings about how great designers they are and what great designs they can do - exactly as the musings from the weaponier in the document you linked. It is however completely irrelevant to proliferation issues of actual power reactors. (Indeed it is virtually always easier and always safer to just build a dedicated production reactor than to try to bend power reactors for nefarious purposes, which makes this whole proliferation issues of power reactors silly, but that is a different topic.)

Sorensen does not "play down the proliferation issues", his thesis is from the horses mouth, mostly from Seaborg's diaries which were never mined for this information. U233 generated in any realistic flux is not pure, and is indeed much worse than Pu240 contaminated Pu239, which is why it was never developed in actual deployed weapon.

"In the case of the molten-salt U-233 breeder reactor, it was proposed to have continual chemical processing of a stream of liquid fuel. Such an arrangement also offers a way to completely bypass the U-232 contamination problem because 27-day half-life Pa- 233 could be separated out before it decays into U-233."

If you don't do the Pa separation, the reactor performance sucks (see the DMSR's performance... it wasn't even fissile self sufficient! And it makes easily-extractable plutonium...)

The fact is, Th-based power reactors can make bombs. It's not the easiest way to get bombs (enrichment is easier). But it's not the hardest either. The fact is, judging nuclear reactor designs against one another is a tough an nuanced job. There are complicated answers for complicated issues. It's fun to think one concept is a slam dunk on all accounts, and the T-MSR is a really good reactor design. But it's not 100% flawless and the Myths page is to just bring people who think it is back to reality so they can be prepared to address the challenges that will arise in engineering a fleet of MSRs.

In this case, the Myth clearly states:

Thorium Myth #3: Thorium reactors cannot make bombs! FALSE!

Lots of amateurs online have claimed that Th reactors cannot make bombs, as you can see in the Wall of Shame. We're just correcting the record for the good of the land. As the article says:

since the consequences of proliferation are so dire, nuclear power plants need to have baseline proliferation safeguards in place. Thorium-powered reactors, whether fluid fueled or not, are no exception.

As for Th-230 (aka "ionium") proposed here, even if you could refine enough of it economically, (there are 17.4 grams of it in 1000 kg of uranium dug up out of the ground), you still could make bombs. Because the decay products of U232 cause the hard gammas, you can purify them out of the uranium. A little U232 doesn't cause any trouble for a bomb until the decay products build up. U232 has a 72 year half-life so you have a decade or so to set off your bomb.

What an absurd statement. You can make a bomb from sea water! Ban sea water! Anything that is less practical to make a bomb out of than enrichment is not (practically) able to make a bomb from.

Why be so technical, this is what people mean:

Thorium reactors cannot (practically) make bombs (if designed correctly). Otherwise, no matter how good it is:

You could take the metal from a thorium reactor and build the casing for a bomb, extract uranium from the sea, enrich it, build a bomb. SEE! A thorium reactor was used to make a bomb! Hur hur hur! It's technically correct.

Maybe you can live on the technically of the law, but practically you are deceptive and misleading.

False! See Myth 3. There's no design that I'm aware of that my experienced radiochemistry and weaponeer colleagues couldn't get bomb material from if they were told to do so.

You've mentioned dilution with Th-230, which certainly might help but appears to be entirely hypothetical and without any real neutronic analysis to back it up. Regardless, you can still purify uranium that contains U-232 and make bombs before the U-232 decay products build up. Am I wrong?

You've mentioned DMSRs, which have U-238 mixed with their U-233. These would make it impossible to extract WG U-233, but alas! There will be weapons-usable Pu239 in there, which is really easy to extract.

So, Myth 3 stands as true. I do not aim to be deceptive or misleading. I just want truth.

Just curious: Would you say that a TMSR doesn't need proliferation safeguards in place at all?

Nothing pointed out in the article differs from what the actual proponents and people who have looked into Thorium say (LFTRs, really)...

There's a difference between informed debate, where all the topics mentioned are understood and contextualised, and uninformed 'debate' by fanboys. The article reacts to the hype.

Nuclear weapons and the cold war impacted all atomic energy planning. Nuclear engineers know the difference between fissile and fertile materials, a fissile core is a given in this kind of reactor. MSRs promise proliferation resistance through low breeding ratios and unattractive fuels, but aren't proliferation "proof". Seawater extraction of Uranium is a really happy 'Plan B'.

Kirk Sorensen talks in-detail about all these topics, as do others in the community. Nothing in life is "perfect", there are always going to be trade-offs.

Nothing pointed out in the article differs from what the actual proponents ... say

Would that this were true. Sadly, I've run into a few thorium nuts who deny all criticism and claim those making them are aligned against any use of thorium, to the point of censoring those voices. Specifically Matt BenDaniel on G+, who's done this to a number of people, myself and others.

Truth is there's all sorts of nuts out there, and they say all sorts of things, many of which aren't true or substantiated.

True enough, but the linked article itself fails to address some points. For example, the concept that MSRs were sidelined due to their unsuitability for bomb-making does have relevance.

The quoted reasons for not going Thorium are bad enough ("but...but... then we can't sell fuel rods") but they don't address why the LWR was developed over the MSR in the first place. And that reason was the ease of making bombs.

I agree. It was more to do with ease of what was available. Uranium enrichment was available (Manhattan Proj), LWR reactor type was a proven model (USN) and they just upscaled those for the first commercial reactors.

LWRs were enabled by some of the technologies developed for military purposes (as indeed were all other reactors), but the reactors themselves are worse than useless when it comes to producing weapons material. That seems to be the confusion - most people understand that the uranium fuel cycle was easier and cheaper to implement because of the work that had been done for weapons, which is one of the reasons it was chosen over thorium for powers reactors. Some thorium advocates get it mixed up however, and claim that LWRs were chosen because they helped produce weapons. This is completely untrue.

Incidentally, the only demonstrated example of breeding using thorium was in an LWR.

Hi. Author of the article here. It's not a hit piece from the uranium industry. You'll find tons of pro-thorium and pro-MSR words on the linked pages (also written by me, not the big bad uranium industry) on that site. It's a clarification piece from a nuclear engineer. Looking forward to your comments though. Please include specific references backing up your points.

Myth #1: I do not believe this is a common myth. I believe this is a misinterpretation of the fact that nuclear subs are what torpedoed the Thorium solutions. The military did have much to say about what was being developed in the 60s and they wanted a reactor that would fit on a sub.

Rickover was one if the biggest proponents of thorium fuels ever… The only time net breeding in a thorium-/U233 fueled reactor has been demonstrated is in a navy-derived reactor, as part of a Rickover project. Nuclear subs did not 'torpedo' thorium solutions, they helped to get them working.

mmmm, no. You are mixing your reactor designs. The first and only thorium molten-salt reactor was built and operated in Oak Ridge National laboratory. It reach criticality in 1965. LFTR is what many people are actually talking about today when they talk about thorium reactors.

I can find no proof of any Navy project working with thorium, nor any proof that Rickover every gave it much consideration as it was not useful for naval ships. If you have some evidence to the contrary, then by all means I would love to read it.

Thorium was explored for 20 years at Oak Ridge National Labs and nowhere else. The last thorium reactor operated at criticality for 5 years before being shutdown.

If you mean MSR when you say thorium, say MSR. The majority (actually the totality so far) of 'thorium reactors' are not molten salt reactors.

Edit: ORNL built two MSRs, neither of which contained thorium, although they demonstrated many of the technologies that would be needed in a thorium-fuelled MSR. Thorium itself has been used in various solid fuelled reactors, although the only one to use an initial U233/thorium core and hence demonstrate breeding was Shippingport.

Other countries to have developed thorium fuels include Russia, Germany, the UK, France and India…

and again the design used at Shippingport was only considered useful by Rickover because he believed it could be used to fuel nuclear ships. That is all that Rickover really cared about. Military usage. At no time did he ever back a system that had only commercial applications such as the LFTR designs.

It was full of thorium. You'd never use thorium in a sub reactor - there would be no point, because they already contain a full core of fissile material (highly enriched uranium). The purpose of the LWBR was to demonstrate that breeding using thorium was possible in an LWR, and potentially commercially realisable. At no point has anybody provided convincing evidence that LFTRs are commercially viable (although that might be the case) while the PWR has been widely deployed. By demonstrating that thorium could be used in a PWR, Rickover made a bigger commercial contribution than most. Of course, uranium turned out to be abundant and there was no need for breeding of any kind, but the fact that it could be done using well-established technology surely helps the case for thorium.

but, the oceanic abundance of Th is 4x10-12%, compared with 3.3x10-7% (mass percent).

If you have access to the ocean, you have access to the beach. It's very, very common to find thorium at a beach. You don't need that much. It's not like coal. These are nuclear bonds, not chemical bonds. Every country could have it's own energy security because it's that abundant.

Not quite - there are certain countries (e.g. India, as mentioned in the article) with tiny Uranium deposits, and several countries that could not be sustainable on Thorium, because there are no known Thorium deposits internally.

However, for the majority of the world, sourcing Thorium would be easier than Uranium in the current economic climate.

India has plenty of thorium and enough fissile materials to run off of thorium especially if they breed thorium.

and several countries that could not be sustainable on Thorium, because there are no known Thorium deposits internally.

Thorium deposits are not necessary. They are definitely helpful, but it's abundant enough in the crust of the earth that you could extract it from the dirt and be net energy positive. And, there are so many countries, no thorium cartel would be successful.

Note the actual sentence - I was mentioning both sides, where India has little Uranium and other countries have little Thorium - the point being that deposits like these are not spread evenly across the Earth's crust, and so global statements about abundance have little relation to statements regarding every country's energy security.

Further, I have not seen any articles contrasting if/how Thorium in the Earth's soil varies (or does not vary) - I would suggest that relative abundance in mineral deposits would be somewhat reflected in its presence in soil/dirt etc.

I happily concede the final point, Thorium cartels would not be successful, but that does not mean its import/export could not be limited - e.g. landlocked countries having to either fly it in (expensive) or have their deposits come through other countries.

As with all problems of global logistics, if it's not sourced locally, you may find problems in the future. Thorium makes it less likely that's going to happen, but I believe countries would be more likely to stockpile and buy from cheaper sources (i.e. mined deposits) than they would be to begin their own ground-sifting programmes, even if it proves energy-positive - the differences in cost would be huge.

As a side-note - do you have any data relating to the relative abundance of Thorium in the "dirt" across the Earth? Most figures I've been able to find (with a quick search) relate to sizeable deposits, so I can't verify if it's equally viable for dirt extraction in all countries.

Nuclear sources are so compact that flying in the fuel would not be cost prohibitive. Maybe it would be more cost effective to import, but competition will keep prices within a reasonable range even if you have to import.

do you have any data relating to the relative abundance of Thorium in the "dirt" across the Earth? Most figures I've been able to find (with a quick search) relate to sizeable deposits, so I can't verify if it's equally viable for dirt extraction in all countries.

I have data for average crust abundance only. I'm not sure I understand what kind of data you are asking for.

When talking about dirt extraction, I would assume that you are talking about low-depth extraction of Thorium - so average Thorium abundances within the crust across different countries of depths of 1km and less would likely be sufficient (or something similar to that).

Only in certain circumstances, and when dealing with certain countries. In general terms it's unlikely, but seems more likely than a Thorium Cartel.

From what I've read (example: this article ) it seems unlikely that such a cartel could exist - the countries with sizeable deposits are politically diverse.

However, I do not know enough about the other contributing factors (e.g. large reserve locations, current mining figures, economic feasibility of other harvest sources - e.g. Granite) to tell you definitively that it could or could not be successful on a global scale.

It seems to have proved unsuccessful when nations attempted to stop North Korea getting Uranium, but perhaps that's not the way to look at it?

That seems a little disingenuous. Sorensen has started a company that is going to build one, so to say that he is ignoring the negatives would imply he's stupid or ignoring his fiduciary duty as head of a company. I would guess his personal wealth is also mostly tied up with said company. I detect the former rocket scientist/engineer as nothing but a straight shooter. He was one of the early credible and vocal thorium proponents.

Disingenuous? I think you're misunderstanding what I'm saying. I don't think Sorensen was ignoring the negatives, nor was he ignorant of them. I think he chose to focus only on the positives in his speech because he was promoting it. /u/When_Doves_Cry on the other hand, seemed to think that Sorensen WAS ignoring the negatives and was disingenuous because of it.